Solid-state imaging device, method of manufacturing the same, and electronic apparatus

ABSTRACT

The present technology relates to a solid-state imaging device that can further reduce the influence the film stress generated in an upper electrode has on a photoelectric conversion film, a method of manufacturing the solid-state imaging device, and an electronic apparatus. 
     A solid-state imaging device includes: a photoelectric conversion film formed on the upper side of a semiconductor substrate; and two or more light shielding films formed at positions higher than the photoelectric conversion film with respect to the semiconductor substrate. The present technology can be applied to solid-state imaging devices, electronic apparatuses, and the like, for example.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/083,050, filed Sep. 7, 2018, which is national stage applicationunder 35 U.S.C. 371 and claims the benefit of PCT Application No.PCT/JP2017/008051 having an international filing date of 1 Mar. 2017,which designated the United States, which PCT application claimed thebenefit of Japanese Patent Application No. 2016-050965 filed 15 Mar.2016, the entire disclosures of each of which are incorporated herein byreference.

TECHNICAL FIELD

The present technology relates to a solid-state imaging device, a methodof manufacturing the solid-state imaging device, and an electronicapparatus. More particularly, the present technology relates to asolid-state imaging device that can further reduce the influence thefilm stress generated in an upper electrode has on a photoelectricconversion film, a method of manufacturing the solid-state imagingdevice, and an electronic apparatus.

BACKGROUND ART

In a solid-state imaging device that has an organic photoelectricconversion film as a photoelectric conversion unit on the upper side ofthe semiconductor substrate, the film stress in the upper electrodemight locally concentrate on the organic photoelectric conversion film.In this case, there is a possibility that property fluctuations of darkcurrent, white defects, and the like of the organic photoelectricconversion film occur in a conspicuous manner.

To counter this, the technique according to Patent Document 1, forexample, is disclosed as a technique for reducing the film stress to begiven to an organic photoelectric conversion film by an upper electrode.Patent Document 1 discloses a technique by which a second upperelectrode is formed on the outer side of a first upper electrode formedabove an organic photoelectric conversion film so that peripheralportions are connected to an insulating film, and the second upperelectrode functions as a film stress adjustment unit. With thisarrangement, the influence the film stress generated in the upperelectrode has on the photoelectric conversion film can be reduced, andproperty fluctuations of dark current and white defects of the organicphotoelectric conversion film can also be reduced.

CITATION LIST Patent Document

-   Patent Document 1: Japanese Patent Application Laid-Open No.    2015-56554

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, in a case where a light shielding film is formed as a higherlayer than the upper electrode, the technique according to PatentDocument 1 is not enough to alleviate the film stress.

The present technology has been made in view of those circumstances, andaims to further reduce the influence the film stress generated in anupper electrode has on a photoelectric conversion film.

Solutions to Problems

A solid-state imaging device according to a first aspect of the presenttechnology includes: a photoelectric conversion film formed on the upperside of a semiconductor substrate; and two or more light shielding filmsformed at positions higher than the photoelectric conversion film withrespect to the semiconductor substrate.

A solid-state imaging device manufacturing method according to a secondaspect of the present technology includes: forming a photoelectricconversion film on the upper side of a semiconductor substrate; andforming two or more light shielding films at positions higher than thephotoelectric conversion film with respect to the semiconductorsubstrate.

An electronic apparatus according to a third aspect of the presenttechnology includes a solid-state imaging device that includes: aphotoelectric conversion film formed on the upper side of asemiconductor substrate; and two or more light shielding films formed atpositions higher than the photoelectric conversion film with respect tothe semiconductor substrate.

In the first through third aspects of the present technology, aphotoelectric conversion film is formed on the upper side of asemiconductor substrate, and two or more light shielding films areformed at positions higher than the photoelectric conversion film withrespect to the semiconductor substrate.

The solid-state imaging device and the electronic apparatus may beindependent devices, or may be modules to be incorporated into otherapparatuses.

Effects of the Invention

According to the first through third aspects of the present technology,the influence the film stress generated in the upper electrode has onthe photoelectric conversion film can be further reduced.

Note that effects of the present technology are not limited to theeffects described herein, and may include any of the effects describedin the present disclosure.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram schematically showing the configuration of asolid-state imaging device to which the present technology is applied.

FIG. 2 is a diagram showing an example cross-sectional configurationaccording to a first embodiment of a solid-state imaging device.

FIG. 3 is a diagram for explaining a method of manufacturing thesolid-state imaging device according to the first embodiment.

FIG. 4 is a diagram for explaining a method of manufacturing thesolid-state imaging device according to the first embodiment.

FIG. 5 is a diagram showing an example cross-sectional configurationaccording to a second embodiment of a solid-state imaging device.

FIG. 6 is a diagram showing an example cross-sectional configurationaccording to a third embodiment of a solid-state imaging device.

FIG. 7 is a diagram showing an example stack structure of a lightshielding film.

FIG. 8 is a block diagram showing an example configuration of an imagingapparatus as an electronic apparatus to which the present technology isapplied.

FIG. 9 is a diagram for explaining examples of use of an image sensor.

MODES FOR CARRYING OUT THE INVENTION

The following is a description of modes (hereinafter referred to asembodiments) for carrying out the present technology. Meanwhile,explanation will be made in the following order.

1. General example configuration of a solid-state imaging device

2. First embodiment of a solid-state imaging device (an exampleconfiguration having a plurality of light shielding films via a sealingfilm)

3. Second embodiment of a solid-state imaging device (an exampleconfiguration including an inter-pixel light shielding film)

4. Third embodiment of a solid-state imaging device (an exampleconfiguration including a plurality of light shielding films, withoutany sealing film interposed between the light shielding films)

5. Example Applications to Electronic Apparatuses

<1. General Example Configuration of a Solid-State Imaging Device>

FIG. 1 schematically shows the configuration of a solid-state imagingdevice to which present technology is applied.

The solid-state imaging device 1 shown in FIG. 1 includes a pixel arrayunit 3 having pixels 2 arranged in a two-dimensional array on asemiconductor substrate 21 using silicon (Si) as the semiconductor, forexample, and a peripheral circuit unit 4 existing around the pixel arrayunit 3. The peripheral circuit unit 4 includes a vertical drive circuit5, column signal processing circuits 6, a horizontal drive circuit 7, anoutput circuit 8, a control circuit 9, and the like.

The pixels 2 each include a photoelectric conversion unit thatphotoelectrically converts incident light, and a plurality of pixeltransistors. The pixel transistors are formed with the four MOStransistors: a transfer transistor, a select transistor, a resettransistor, and an amplification transistor, for example.

The control circuit 9 receives an input clock and data that designatesan operation mode and the like, and also outputs data such as internalinformation about the solid-state imaging device 1. Specifically, inaccordance with a vertical synchronization signal, a horizontalsynchronization signal, and a master clock, the control circuit 9generates a clock signal and a control signal that serve as thereferences for operations of the vertical drive circuit 5, the columnsignal processing circuits 6, the horizontal drive circuit 7, and thelike. The control circuit 9 then outputs the generated clock signal andcontrol signal to the vertical drive circuit 5, the column signalprocessing circuits 6, the horizontal drive circuit 7, and the like.

The vertical drive circuit 5 is formed with a shift register, forexample, selects a predetermined pixel drive line 11, supplies a pulsefor driving the pixels 2 connected to the selected pixel drive line 11,and drives the pixels 2 on a row-by-row basis. Specifically, thevertical drive circuit 5 sequentially selects and scans the respectivepixels 2 of the pixel array unit 3 on a row-by-row basis in the verticaldirection, and supplies pixel signals based on the signal chargesgenerated in accordance with the amounts of light received in thephotoelectric conversion units of the respective pixels 2, to the columnsignal processing circuits 6 through vertical signal lines 12.

The column signal processing circuits 6 are provided for the respectivecolumns of the pixels 2, and perform signal processing such asdenoising, on a column-by-column basis, on signals that are output fromthe pixels 2 of one row. For example, the column signal processingcircuits 6 perform signal processing such as correlated double sampling(CDS) for removing fixed pattern noise inherent to pixels, and ADconversion.

The horizontal drive circuit 7 is formed with a shift register, forexample. The horizontal drive circuit 7 sequentially selects therespective column signal processing circuits 6 by sequentiallyoutputting horizontal scan pulses, and causes the respective columnsignal processing circuits 6 to output pixel signals to a horizontalsignal line 13.

The output circuit 8 performs signal processing on signals sequentiallysupplied from the respective column signal processing circuits 6 throughthe horizontal signal line 13, and outputs the processed signals. Theoutput circuit 8 might perform only buffering, or might perform blacklevel control, column variation correction, various kinds of digitalsignal processing, and the like, for example. An input/output terminal10 exchanges signals with the outside.

The solid-state imaging device 1 having the above structure is aso-called column AD-type CMOS image sensor in which the column signalprocessing circuits 5 that perform CDS and AD conversion are providedfor the respective pixel columns.

2. First Embodiment of a Solid-State Imaging Device

FIG. 2 is a diagram showing an example cross-sectional configurationaccording to a first embodiment of a solid-state imaging device.

Note that the pixel array unit 3 shown in FIG. 2 is a pixelcross-sectional structure of two pixels due to space limitation.

The semiconductor substrate 21 is formed with a semiconductor region 41of a first conductivity type (the P-type, for example) and semiconductorregions 42 and 43 of a second conductivity type (the N-type, forexample). As the semiconductor regions 42 and 43 of the secondconductivity type are stacked in the depth direction on a pixel-by-pixelbasis in the semiconductor region 41 of the first conductivity type,photodiodes PD1 and PD2 are formed with PN junctions in the depthdirection. The photodiode PD1 having the semiconductor region 42 as thecharge accumulation region is a photoelectric conversion unit thatreceives blue light and performs photoelectric conversion, and thephotodiode PD2 having the semiconductor region 43 as the chargeaccumulation region is a photoelectric conversion unit that receives redlight and performs photoelectric conversion.

A multilayer wiring layer 46 formed with a plurality of pixeltransistors Tr that perform reading of charges accumulated in thephotodiodes PD1 and PD2, and the like, a plurality of wiring layers 44,and an interlayer insulating film 45 is formed on the front surface sideof the semiconductor substrate 21, which is the lower side in FIG. 2.

Meanwhile, a photoelectric conversion unit 52 is formed on the backsurface side of the semiconductor substrate 21, which is the upper sidein FIG. 2, via a transparent insulating film 51. The photoelectricconversion unit 52 is formed by stacking an upper electrode 61, aphotoelectric conversion film 62, and a lower electrode 63, and thephotoelectric conversion film 62 is interposed between the upperelectrode 61 and the lower electrode 63. The upper electrode 61 isformed to be shared by all the pixels of the pixel array unit 3, and thelower electrode 63 is formed separately for each pixel of the pixelarray unit 3.

The transparent insulating film 51 is formed with one or a plurality oflayers using a material such as silicon oxide (SiO2), silicon nitride(SiN), silicon oxynitride (SiON), or hafnium oxide (HfO2), for example.

A transparent conductive material such as indium tin oxide (ITO), zincoxide, or indium zinc oxide, for example, is used as the material of theupper electrode 61 and the lower electrode 63. The upper electrode 61and the lower electrode 63 are designed to have a thickness of about 50nm, for example.

The photoelectric conversion film 62 receives green light, and performsphotoelectric conversion. In the photoelectric conversion film 62, anexample of the material sensitive only to green light is a combinationof organic materials that are a quinacridone compound (anelectron-donating material) and a perylene compound (anelectron-accepting material), for example. The photoelectric conversionfilm 62 is designed to have a thickness of about 155 nm, for example.

The lower electrode 63 is connected to metal wiring lines 53 penetratingthe transparent insulating film 51, and the metal wiring lines 53 areconnected to conductive plugs 47 penetrating the semiconductor region 41of the semiconductor substrate 21. The metal wiring lines 53 are formedwith a material, such as tungsten (W), aluminum (Al), or copper (Cu).

The conductive plugs 47 are connected to charge accumulation portions 48formed in a semiconductor region of the second conductivity type (theN-type, for example) in the vicinity of the interface on the frontsurface side of the semiconductor region 41. Note that, although notshown in the drawings, the outer circumferences of the conductive plugs47 are insulated with an insulating film of SiO2, SiN, or the like.

The electric charges generated through photoelectric conversion in thephotoelectric conversion unit 52 are transferred to the chargeaccumulation portions 48 via the metal wiring lines 53 and theconductive plugs 47. The charge accumulation portions 48 temporarilyaccumulate the electric charges photoelectrically converted by thephotoelectric conversion unit 52, until the electric charges are readout.

A sealing film (protective film) 54 is formed on the upper side of theupper electrode 61 of the pixel array unit 3 and on the upper side ofthe transparent insulating film 51 of the peripheral circuit unit 4.Further, a first light shielding film 55A and a second light shieldingfilm 55B are stacked above the sealing film 54 via a sealing film(protective film) 56 interposed therebetween.

The respective thicknesses of the first light shielding film 55A and thesecond light shielding film 55B are set so as to achieve alight-shielding function with the total thickness of these two films. Asa light shielding film 55 is formed and divided into a plurality oflayers as described above, it is possible to alleviate the stress at thetime of formation of the respective light shielding films 55 of thefirst light shielding film 55A and the second light shielding film 55B.

The sealing films 54 and 56 are formed with an inorganic material havingoptical transparency. For example, the sealing films 54 and 56 areformed with single-layer films including silicon nitride (SiN), siliconoxynitride (SiON), aluminum oxide (ALO), aluminum nitride (AlN), or thelike, or film stacks of two or more of those films.

As shown in FIG. 2, the first light shielding film 55A, which is thelower one of the first light shielding film 55A and the second lightshielding film 55B, and is closer to the photoelectric conversion unit52, is connected to the upper electrode 61 at a predetermined positionof the peripheral circuit unit 4, and also serves as a metal wiring linefor applying a predetermined bias voltage to the upper electrode 61. Amaterial having a low transmittance with respect to visible light, suchas tungsten (W), titanium (Ti), aluminum (Al), or copper (Cu), forexample, is used as the material of the first light shielding film 55Aand the second light shielding film 55B, but this aspect will bedescribed later in detail.

In the pixel array unit 3, an on-chip lens 58 is formed for each pixelon the sealing film 56. A silicon nitride (SiN) film, or a resinmaterial such as a styrene resin, an acrylic resin, a styrene-acryliccopolymer resin, or a siloxane resin, for example, is used as thematerial of the on-chip lenses 58. The sealing film 56 and the on-chiplenses 58 can be formed with the same material.

The solid-state imaging device 1 formed as described above is aback-illuminated CMOS solid-state imaging device in which light entersfrom the back surface side on the opposite side from the front surfaceside of the semiconductor substrate 21 having the pixel transistors Trformed thereon.

As shown in FIG. 2, in the solid-state imaging device 1 according to thefirst embodiment, the light shielding film 55 is formed at a higherposition than the photoelectric conversion film 62 with respect to thesemiconductor substrate 21, and is formed with a plurality of layersthat are the first light shielding film 55A and the second lightshielding film 55B. With this arrangement, even in a case where thelight shielding film 55 is formed above the upper electrode 61 of thephotoelectric conversion unit 52, it is possible to reduce the influencethe film stress generated in the upper electrode 61 has on thephotoelectric conversion film 62. Further, as the influence the filmstress generated in the upper electrode 61 has on the photoelectricconversion film 62 is reduced, property fluctuations of dark current andwhite defects of the photoelectric conversion film 62 can also bereduced.

<Manufacturing Method>

Referring now to FIGS. 3 and 4, a method of manufacturing thesolid-state imaging device 1 according to the first embodiment shown inFIG. 2 is described.

First, as shown in A of FIG. 3, after the photodiodes PD1 and PD2, theconductive plugs 47, and the like are formed in a predetermined regionof the semiconductor substrate 21, the multilayer wiring layer 46including the plurality of pixel transistors Tr is formed on the frontsurface side of the semiconductor substrate 21.

After that, the photoelectric conversion unit 52 and the sealing film 54are formed on the back surface side of the semiconductor substrate 21.At a predetermined position in the peripheral circuit unit 4, an openingis then formed in the sealing film 54, so that the upper electrode 61 isexposed. The first light shielding film 55A is then formed by asputtering method or a chemical vapor deposition (CVD) method, forexample, so as to cover the upper surface of the sealing film 54including the opening portion.

As shown in B of FIG. 3, of the first light shielding film 55A formed onthe entire planar region of the pixel array unit 3 and the peripheralcircuit unit 4, the portion located in the pixel array unit 3 isremoved, together with the portion of the sealing film 54 located underthe portion of the first light shielding film 55A, by etching.

Next, as shown in C of FIG. 3, the sealing film 56 is formed on theentire planar region of the pixel array unit 3 and the peripheralcircuit unit 4 by a plasma CVD method, for example.

Next, as shown in A of FIG. 4, the second light shielding film 55B to bethe second layer of the light shielding film 55 is formed on the uppersurface of the formed sealing film 56 by a sputtering method or a CVDmethod, for example.

As shown in B of FIG. 4, of the second light shielding film 55B formedon the entire surface, the portion located in the pixel array unit 3 isthen subjected to etching. After that, as shown in C of FIG. 4, thesealing film 56 is again formed on the entire planar region of the pixelarray unit 3 and the peripheral circuit unit 4.

After C of FIG. 4, the on-chip lenses 58 for the respective pixels areformed on the upper surface of the sealing film 56 in the pixel arrayunit 3. Thus, the solid-state imaging device 1 shown in FIG. 2 iscompleted.

The film stress of the light shielding film 55 increases as thethickness of the light shielding film 55 becomes greater. Also, the filmstress of the light shielding film 55 is alleviated when the lightshielding film 55 in the pixel array unit 3 is removed by etching.Therefore, the light shielding layer is formed as a two-layer structureof the first light shielding film 55A and the second light shieldingfilm 55B, the thickness of each layer is reduced, and the formation andthe etching of the light shielding film 55 are repeatedly performed.Thus, the photoelectric conversion film 62 can be protected from a largestress at the time of the formation of the light shielding layer.

3. Second Embodiment of a Solid-State Imaging Device

FIG. 5 is a diagram showing an example cross-sectional configurationaccording to a second embodiment of a solid-state imaging device.

Note that, in FIG. 5, the components equivalent to those of the firstembodiment shown in FIG. 2 are denoted by the same reference numerals asthose used in FIG. 2, and explanation of them will not be unnecessarilyrepeated.

The second embodiment shown in FIG. 5 differs from the above describedfirst embodiment in that first light shielding film 55A and the secondlight shielding film 55B are also formed between the pixels that are theboundaries between the respective pixels 2 of the pixel array unit 3,and the first light shielding film 55A and the second light shieldingfilm 55B each further have the functions of an inter-pixel lightshielding film. Other aspects of the configuration are similar to thoseof the above described first embodiment.

In other words, in the above described first embodiment, the first lightshielding film 55A and the second light shielding film 55B have anopening in the entire region of the effective pixel region of the pixelarray unit 3. In the second embodiment shown in FIG. 5, on the otherhand, the effective pixel region of the pixel array unit 3 has openingsfor the respective pixels.

In the second embodiment as described above, the light shielding film 55is also divided into a plurality of layers and is formed with the firstlight shielding film 55A and the second light shielding film 55B. Thus,it is possible to reduce the influence the film stress generated in theupper electrode 61 has on the photoelectric conversion film 62. Further,as the influence the film stress generated in the upper electrode 61 hason the photoelectric conversion film 62 is reduced, propertyfluctuations of dark current and white defects of the photoelectricconversion film 62 can also be reduced.

4. Third Embodiment of a Solid-State Imaging Device

FIG. 6 is a diagram showing an example cross-sectional configurationaccording to a third embodiment of a solid-state imaging device.

Note that, in FIG. 6, the components equivalent to those of the firstembodiment shown in FIG. 2 are also denoted by the same referencenumerals as those used in FIG. 2, and explanation of them will not beunnecessarily repeated.

In the first embodiment shown in FIG. 2, the sealing film 56 is formedbetween the first light shielding film 55A and the second lightshielding film 55B. In the third embodiment shown in FIG. 6, on theother hand, the sealing film 56 is not formed between the first lightshielding film 55A and the second light shielding film 55B, and thefirst light shielding film 55A and the second light shielding film 55Bare directly attached to each other in the stack structure, whichdiffers from the above described first embodiment. The third embodimentalso differs from the above described first embodiment in that thesecond light shielding film 55B covers the end face of the first lightshielding film 55A on the side of the pixel array unit 3, which is theeffective pixel region side. Other aspects of the configuration aresimilar to those of the above described first embodiment.

The reason that the end face of the first light shielding film 55A onthe effective pixel region side is covered with the second lightshielding film 55B is that, when etching is performed on the first lightshielding film 55A, the portion of the sealing film 54 located under thefirst light shielding film 55A is also removed.

In the third embodiment as described above, the light shielding film 55is also divided into a plurality of layers and is formed with the firstlight shielding film 55A and the second light shielding film 55B. Thus,it is possible to reduce the influence the film stress generated in theupper electrode 61 has on the photoelectric conversion film 62. Further,as the influence the film stress generated in the upper electrode 61 hason the photoelectric conversion film 62 is reduced, propertyfluctuations of dark current and white defects of the photoelectricconversion film 62 can also be reduced.

<Example Configuration of a Light Shielding Film>

FIG. 7 shows an example of the stack structure of a single-layer lightshielding film 55 that can be adopted as a first light shielding film55A or a second light shielding film 55B.

As shown in FIG. 7, the first light shielding film 55A or the secondlight shielding film 55B can be formed as a single-layer structure usingone material such as tungsten (W) or aluminum (Al), or can be formed asa two-layer structure using two materials, such as a two-layer structureof tungsten and titanium (W/Ti) or a two-layer structure of aluminum andtitanium (Al/Ti), for example. Furthermore, the first light shieldingfilm 55A or the second light shielding film 55B can be formed as athree- or four-layer structure using two or more materials, such as athree-layer structure of aluminum, TiN, and titanium (Al/TiN/Ti), or afour-layer structure of TiN, aluminum, TiN, and titanium(TiN/Al/TiN/Ti).

As for the thickness of the light shielding film 55, in a case where thefirst light shielding film 55A or the second light shielding film 55B isformed with one layer of tungsten, for example, the thickness thatsatisfies the light shielding function is 250 nm, as shown in FIG. 7. Ina case where the first light shielding film 55A or the second lightshielding film 55B is formed with one layer of aluminum, the thicknessis 108 nm. In this manner, the total thickness of the single-layer lightshielding film 55 varies depending on the adopted materials and theadopted combination of materials.

Although the thicknesses of the first light shielding film 55A and thesecond light shielding film 55B may be the same, the thickness of thefirst light shielding film 55A on the lower side is preferably thinner.The material(s) and the stack structure (the number of layers) may beeither the same or different between the first light shielding film 55Aand the second light shielding film 55B.

<5. Example Applications to Electronic Apparatuses>

The present technology is not necessarily applied to a solid-stateimaging device. Specifically, the present technology can be applied toany electronic apparatus using a solid-state imaging device as an imagecapturing unit (a photoelectric conversion unit), such as an imagingapparatus like a digital still camera, a video camera, or the like, amobile terminal device having an imaging function, or a copying machineusing a solid-state imaging device as the image reader. A solid-stateimaging device may be in the form of a single chip, or may be in theform of a module that is formed by packaging an imaging unit and asignal processing unit or an optical system, and has an imagingfunction.

FIG. 8 is a block diagram showing an example configuration of an imagingapparatus as an electronic apparatus to which the present technology isapplied.

The imaging apparatus 100 shown in FIG. 8 includes an optical unit 101formed with lenses and the like, a solid-state imaging device (animaging device) 102 having the configuration of the solid-state imagingdevice 1 shown in FIG. 1, and a digital signal processor (DSP) circuit103 that is a camera signal processor circuit. The imaging apparatus 100also includes a frame memory 104, a display unit 105, a recording unit106, an operation unit 107, and a power supply unit 108. The DSP circuit103, the frame memory 104, the display unit 105, the recording unit 106,the operation unit 107, and the power supply unit 108 are connected toone another via a bus line 109.

The optical unit 101 gathers incident light (image light) from anobject, and forms an image on the imaging surface of the solid-stateimaging device 102. The solid-state imaging device 102 converts theamount of the incident light, which has been gathered as the image onthe imaging surface by the optical unit 101, into an electrical signalfor each pixel, and outputs the electrical signal as a pixel signal.This solid-state imaging device 102 can be the solid-state imagingdevice 1 shown in FIG. 1, which is a solid-state imaging device in whichthe light shielding layer is divided into a plurality of light shieldingfilms 55 (the first light shielding film 55A and the second lightshielding film 55B), so that the influence the film stress to begenerated in the upper electrode 61 of the photoelectric conversion unit52 has on the photoelectric conversion film 62 is reduced.

The display unit 105 is formed with a flat-panel display such as aliquid crystal display (LCD) or an organic electro-luminescence (EL)display, for example, and displays a moving image or a still imageformed by the solid-state imaging device 102. The recording unit 106records the moving image or the still image formed by the solid-stateimaging device 102 into a recording medium such as a hard disk or asemiconductor memory.

When operated by a user, the operation unit 107 issues operatinginstructions as to various functions of the imaging apparatus 100. Thepower supply unit 108 supplies various power sources as the operationpower sources for the DSP circuit 103, the frame memory 104, the displayunit 105, the recording unit 106, and the operation unit 107, asappropriate.

As described above, the solid-state imaging device 1 to which one of theabove described embodiments or a combination the embodiments is appliedis used as the solid-state imaging device 102. Thus, it is possible toreduce the influence the film stress generated in the upper electrode 61of the photoelectric conversion unit 52 has on the photoelectricconversion film 62. Further, as the influence the film stress generatedin the upper electrode 61 has on the photoelectric conversion film 62 isreduced, property fluctuations of dark current and white defects of thephotoelectric conversion film 62 can also be reduced. Accordingly, thequality of captured images can also be increased in the imagingapparatus 100, which is a video camera, a digital still camera, acameral module for mobile devices such as portable telephone devices, orthe like.

<Examples of Use of an Image Sensor>

FIG. 9 is a diagram showing examples of use of an image sensor using theabove described solid-state imaging device 1.

An image sensor using the above described solid-state imaging device 1can be used in various cases where light, such as visible light,infrared light, ultraviolet light, or X-rays, is to be sensed, as listedbelow, for example.

-   -   Devices configured to take images for appreciation activities,        such as digital cameras and portable devices with camera        functions.    -   Devices for transportation use, such as vehicle-mounted sensors        configured to take images of the front, the back, the        surroundings, the inside, and the like of an automobile to        perform safe driving such as an automatic stop or recognize a        driver's condition and the like, surveillance cameras for        monitoring running vehicles and roads, and ranging sensors for        measuring distances between vehicles or the like.    -   Devices to be used in conjunction with home electric appliances,        such as television sets, refrigerators, and air conditioners, to        take images of gestures of users and operate the appliances in        accordance with the gestures.    -   Devices for medical care use and health care use, such as        endoscopes and devices for receiving infrared light for        angiography.    -   Devices for security use, such as surveillance cameras for crime        prevention and cameras for personal authentication.    -   Devices for beauty care use, such as skin measurement devices        configured to take images of the skin and microscopes for        imaging the scalp.    -   Devices for sporting use, such as action cameras and wearable        cameras for sports and the like.    -   Devices for agricultural use such as cameras for monitoring        conditions of fields and crops.

Embodiments of the present technology are not limited to the abovedescribed embodiments, and various modifications can be made to themwithout departing from the scope of the present technology.

For example, it is possible to adopt a combination of all or some of theabove described embodiments.

Further, for example, in the above described examples in the respectiveembodiments, the light shielding layer has a two-layer structure of thefirst light shielding film 55A and the second light shielding film 55B.However, the light shielding layer may be divided into three or morelayers.

The above described solid-state imaging device 1 is a verticalspectroscopic solid-state imaging device that photoelectrically convertsgreen wavelength light with the photoelectric conversion unit 52 formedoutside the semiconductor substrate 21, and photoelectrically convertsblue and red wavelength light with the photodiodes PD1 and PD2 in thesemiconductor substrate 21, for example. Instead of such a verticalspectroscopic solid-state imaging device, the solid-state imaging device1 can also adopt a configuration in which a so-called panchromatic filmhaving sensitivity over the entire wavelength range of visible light isused as the photoelectric conversion film 62, and color filters in theBayer array or the like are formed above the photoelectric conversionfilm 62. In this case, the photodiodes PD1 and PD2 are not formed in thesemiconductor substrate 21, and accordingly, the lower electrode 63 canbe formed with a metal such as aluminum, vanadium, gold, silver,platinum, iron, cobalt, carbon, nickel, tungsten, palladium, magnesium,calcium, tin, lead, titanium, yttrium, lithium, ruthenium, or manganese,or an alloy of some of those alloys, for example.

Also, in the above described solid-state imaging device 1, thephotoelectric conversion unit 52 formed outside the semiconductorsubstrate 21 photoelectrically converts green wavelength light. However,the photoelectric conversion unit 52 may be designed tophotoelectrically convert light of wavelength of some other color. Inother words, in the vertical spectroscopic solid-state imaging device 1,the colors of wavelength light to be photoelectrically converted by thethree photoelectric conversion units may be switched as appropriate.

The material in a case where the photoelectric conversion unit 52 isformed with a photoelectric conversion film 62 having sensitivity onlyto red can be a combination of organic materials including aphthalocyanine compound (an electron-donating material) and afluorine-substituted phthalocyanine compound (an electron-acceptingmaterial), for example.

The material in a case where the photoelectric conversion unit 52 isformed with a photoelectric conversion film 62 having sensitivity onlyto blue can be a combination of organic materials including a coumarincompound (an electron-donating material) and a silole compound (anelectron-accepting material), for example.

Alternatively, instead of an organic photoelectric conversion material,an inorganic photoelectric conversion material may be adopted as thematerial of the photoelectric conversion film 62. Examples of suchinorganic photoelectric conversion materials include crystallinesilicon, amorphous silicon, CIGS (Cu, In, Ga, and Se compounds), CIS(Cu, In, and Se compounds), chalcopyrite structured semiconductors, andcompound semiconductors such as GaAs.

In the above described examples, the solid-state imaging device 1 isformed with the single semiconductor substrate 21. However, thesolid-state imaging device 1 may be a stack structure formed with two orthree semiconductor substrates.

In the solid-state imaging devices in the above described examples, thefirst conductivity type is the P-type, the second conductivity type isthe N-type, and electrons are used as signal charges. However, thepresent technology can also be applied to solid-state imaging devices inwhich holes are used as signal charges. That is, the first conductivitytype can be the N-type, the second conductivity type can be the P-type,and the conductivity types of the above described respectivesemiconductor regions can be reversed.

The present technology can be applied not only to solid-state imagingdevices that sense an incident light quantity distribution of visiblelight and form an image in accordance with the distribution, but also tosolid-state imaging devices (physical quantity distribution sensors) ingeneral, such as a solid-state imaging device that senses an incidentquantity distribution of infrared rays, X-rays, particles, or the like,and forms an image in accordance with the distribution, or a fingerprintsensor that senses a distribution of some other physical quantity in abroad sense, such as pressure or capacitance, and forms an image inaccordance with the distribution.

Furthermore, the present technology can be applied not only tosolid-state imaging devices but also to semiconductor devices havingsome other semiconductor integrated circuits.

Note that the advantageous effects described in this specification aremerely examples, and the advantageous effects of the present technologyare not limited to them and may include effects other than thosedescribed in this specification.

Note that the present technology can also be embodied in theconfigurations described below.

(1)

A solid-state imaging device including:

a photoelectric conversion film formed on an upper side of asemiconductor substrate; and

at least two light shielding films formed at positions higher than thephotoelectric conversion film with respect to the semiconductorsubstrate.

(2)

The solid-state imaging device according to (1), in which the at leasttwo light shielding films have an opening in an entire region of aneffective pixel region.

(3)

The solid-state imaging device according to (1), in which the at leasttwo light shielding films have openings for respective pixels in aneffective pixel region, and include an inter-pixel light shielding film.

(4)

The solid-state imaging device according to any of (1) to (3), furtherincluding

a sealing film between respective light shielding films of the at leasttwo light shielding films.

(5)

The solid-state imaging device according to any of (1) to (3), in whichthe at least two light shielding films are stacked, without anotherlayer being interposed between the at least two light shielding films.

(6)

The solid-state imaging device according to (5), in which

the at least two light shielding films are formed with two lightshielding films, the two light shielding films being a first lightshielding film on a side of the semiconductor substrate and a secondlight shielding film formed on a light incident side of the first lightshielding film, and

an end face of the first light shielding film on an effective pixelregion side is covered with the second light shielding film.

(7)

The solid-state imaging device according to any of (1) to (6), in whichthe at least two light shielding films are formed with two lightshielding films.

(8)

The solid-state imaging device according to any of (1) to (7), in whichthe photoelectric conversion film is an organic photoelectric conversionfilm containing an organic material.

(9)

A method of manufacturing a solid-state imaging device, including:

forming a photoelectric conversion film on an upper side of asemiconductor substrate; and

forming at least two light shielding films at positions higher than thephotoelectric conversion film with respect to the semiconductorsubstrate.

(10)

An electronic apparatus including

a solid-state imaging device including:

a photoelectric conversion film formed on an upper side of asemiconductor substrate; and

at least two light shielding films formed at positions higher than thephotoelectric conversion film with respect to the semiconductorsubstrate.

REFERENCE SIGNS LIST

-   1 Solid-state imaging device-   2 Pixel-   3 Pixel array unit-   21 Semiconductor substrate-   41 through 43 Semiconductor region-   46 Multilayer wiring layer-   51 Transparent insulating film-   52 Photoelectric conversion unit-   54 Sealing film-   55A First light shielding film-   55B Second light shielding film-   55 Light shielding film-   56 Sealing film-   61 Upper electrode-   62 Photoelectric conversion film-   63 Lower electrode-   100 Imaging apparatus-   102 Solid-state imaging device

1. A solid-state imaging device, comprising: a photoelectric conversionfilm formed above an upper side of a semiconductor substrate; at leasttwo light shielding films formed at positions higher than thephotoelectric conversion film; and a protective film formed on an upperportion and side portions of an upper electrode of a pixel array unit,wherein the protective film is provided between the upper electrode andthe at least two light shielding films.
 2. The solid-state imagingdevice according to claim 1, wherein either of the at least two lightshielding films is formed with one light shielding film made of tungstenor aluminum.
 3. The solid-state imaging device according to claim 2,wherein both of the at least two light shielding films are formed withone light shielding film made of tungsten or aluminum.
 4. Thesolid-state imaging device according to claim 1, wherein either of theat least two light shielding films is formed with at least two lightshielding films made of combinations of two or more materials from thegroup consisting of tungsten, titanium or aluminum.
 5. The solid-stateimaging device according to claim 4, wherein both of the at least twolight shielding films are formed with at least two light shielding filmsmade of combinations of two or more materials from the group consistingof tungsten, titanium or aluminum.
 6. The solid-state imaging deviceaccording to claim 1, wherein one of the at least two light shieldingfilms is thinner than another of the at least two light shielding films.7. The solid-state imaging device according to claim 6, wherein thelight shielding film of the at least two light shielding films closer tothe upper electrode is the thinner light shielding film.
 8. Thesolid-state imaging device according to claim 1, wherein the at leasttwo light shielding films have openings for respective pixels in aneffective pixel region and include an inter-pixel light shielding film.9. The solid-state imaging device according to claim 1, wherein the atleast two light shielding films have an opening in an entire region ofan effective pixel region.
 10. The solid-state imaging device accordingto claim 1, further comprising a sealing film between respective lightshielding films of the at least two light shielding films.
 11. A methodof manufacturing a solid-state imaging device, comprising: forming aphotoelectric conversion film above an upper side of a semiconductorsubstrate; forming at least two light shielding films at positionshigher than the photoelectric conversion film with respect to thesemiconductor substrate; and forming a protective film on an upperportion and side portions of an upper electrode of a pixel array unit,wherein the protective film is provided between the upper electrode andthe at least two light shielding films.
 12. The method of manufacturinga solid-state imaging device according to claim 11, wherein either ofthe at least two light shielding films is formed with one lightshielding film made of tungsten or aluminum.
 13. The method ofmanufacturing a solid-state imaging device according to claim 12,wherein both of the at least two light shielding films are formed withone light shielding film made of tungsten or aluminum.
 14. The method ofmanufacturing a solid-state imaging device according to claim 11,wherein either of the at least two light shielding films is formed withat least two light shielding films made of combinations of two or morematerials from the group consisting of tungsten, titanium or aluminum.15. The method of manufacturing a solid-state imaging device accordingto claim 14, wherein both of the at least two light shielding films areformed with at least two light shielding films made of combinations oftwo or more materials from the group consisting of tungsten, titanium oraluminum.
 16. An electronic apparatus, comprising: a solid-state imagingdevice including: a photoelectric conversion film formed above an upperside of a semiconductor substrate; at least two light shielding filmsformed at positions higher than the photoelectric conversion film withrespect to the semiconductor substrate; and a protective film formed onan upper portion and side portions of an upper electrode of a pixelarray unit, wherein the protective film is provided between the upperelectrode and the at least two light shielding films.
 17. The electronicapparatus according to claim 16, wherein either of the at least twolight shielding films is formed with one light shielding film made oftungsten or aluminum.
 18. The electronic apparatus according to claim17, wherein both of the at least two light shielding films are formedwith one light shielding film made of tungsten or aluminum.
 19. Theelectronic apparatus according to claim 16, wherein either of the atleast two light shielding films is formed with at least two lightshielding films made of combinations of two or more materials from thegroup consisting of tungsten, titanium or aluminum.
 20. The electronicapparatus according to claim 19, wherein both of the at least two lightshielding films are formed with at least two light shielding films madeof combinations of two or more materials from the group consisting oftungsten, titanium or aluminum.